The present invention relates generally to data communication networks, and more specifically, to a method and system for transporting Ten Gigabit Ethernet (GE) over OTN (Optical Transport Network)
Efficient transfer of traffic requires a network designed in conformance with conventional voice network and suitable for transferring variable length packets. Conventionally, there is SONET/SDH as a digital network for WAN (Wide Area Network). These networks commonly use technology for encapsulating data of a higher-layer protocol such as Media Access Control (MAC) frames on Ethernet and transmitting the data on a transport network. GFP, defined in ITU-T G.7041, is a generic mechanism for protocol data unit (PDU) oriented client signal adaptation to enable data mapping into a SONET/SDH virtual container and specifies the framing format for a number of link protocols, such as Ethernet. GFP provides a means to map different signals into SONET/SDH and the optical transport network. It also defines the frame formats for protocol data units (PDUs) transferred between GFP initiation and termination points, as well as the mapping procedure for the client signals into GFP. GFP supports many types of packets, including Ethernet frames. FIG. 1 illustrates the mapping of an Ethernet MAC frame 12 into GFP frame 14. As shown in FIG. 1, the Start of Frame Delimiter and 7 bytes of preamble are removed (total of 8 bytes) and replaced with GFP overhead.
ITU recommendation G.709 (“Interface for the Optical Transport Network (OTN))” builds on the experience and benefits gained from SDH and SONET to provide a route to the next-generation optical network. The ITU-T G.709 frame includes three parts: overhead area for operation, administration, and maintenance functions; payload area for customer data; and forward error correction (FEC). FEC provides additional coded data to enable error checking and correction by a receiving device.
Transport of 10 GE LAN over OTN is becoming an important feature. ITU-T G.709 links running at an appropriate rate can carry 10 Gigabit Ethernet and future rate Ethernet. However, there are difficulties with the transport of 10 Gigabit Ethernet LAN over OTN. For example, 10 Gigabit Ethernet LAN without 64/66 encoding has a line frequency of 10 Gb/s, while payload of OTN has a frequency of 9.995276962 Gb/s. Since 10 Gigabit Ethernet LAN has a higher frequency as compared with the OTN payload, an operation is required to reduce the incoming frequency.
Conventional solutions to this problem include increasing the output frequency or using bytes defined as overhead by G.709 to transport payload. Another option is to add a pause mechanism to reduce the maximum data throughput. However, each of these conventional methods has drawbacks. For example, addition of a pause mechanism requires a large amount of memory.